Material weighing and delivering apparatus



Jam 5, 1954 R. E. EVANS ETAL MATERIAL WEIGHING AND DELIVERING APPARATUS 2 sheets-sheet i Filed Jan. 6, 1951 Jan. 5, 1954 Filed Jan. 6, 1951 R. E. EVANS ETAL MATERIAL WEIGHING AND DELIVERING APPARATUS 2 Sheets-Shee't 2 @g3 BY INVENTORS ATTORNEYS Patented Jan. 5, 1954 UNITED STATES PATENT OFFICE MATERIAL WEIGHING AND DELIVERING APPARATUS Application January 6, 1951, Serial No. 204,810

3 Claims.

This invention relates to means for securing the delivery of a plurality of materials in desired proportions, the particular embodiment of the invention to be described being designed for the purpose of effecting proportioned delivery of titanium sponge and an alloying ingredient to a melting furnace. The gravimetric density, granulation, and other rheological characteristics of the ingredients are such that it is impracticable to prepare a homogeneous mixture in the desired proportions in a granular, comminuted, or pulverulent form. A constant delivery of the correct proportions is essential when any substantial mixing in the molten state is diflicult.

The present invention contemplates providing separate containers for the materials to be delivered, such as one container for titanium sponge and a second container for an alloying ingredient, balancing the two containers and associated parts on a scale beam during delivery of the materials, and regulating the delivery of one of the materials according to the departure of the scale beam from balance; that is, the contents of each container are constantly weighed, and a correction is made in the rate of delivery of material from one of the containers in accordance with any deviation from standard proportions in the weights f materia1 remaining in the containers. The delivery means is preferably of a mechanical character, such as feed screws, and the rate of rotation of one of the feed screws is controlled by a servo-motor which in turn is controlled by the departure from balance of the scale beam.

In the drawings:

Fig. 1 is a fragmentary elevation, some parts of which are in section and some merely diagrammatically represented.

Fig. 1a. is a fragmentary view, partly in section and with parts broken away, of a hopper employed with the apparatus shown in Fig. l.

Fig. 1b is also a fragmentary showing of `means for supporting the hopper of Fig. lo upon the apparatus of Fig. 1.

Fig. 1c is a fragmentary showing, partly in section and with parts broken away, of the bottom portion of the hopper shown in Fig. 1a, together with means for feeding material therefrom.

Fig. 1d is a further fragmentary showing, also partly in section and with parts broken away, of a second hopper, and outfeed means therefor, employed with the apparatus of Fig. 1, and also showing the means for associating a, discharge tube of such hopper with a melting furnace.

Fig. 2 is a section on line 2 2 of Fig. l.

Fig. 3 is a diagrammatic representation of the mechanism by which the feed screws are driven and one such feed screw is controlled by the deection of the scale beam.

The hoppers and associated parts are supported from a pivoted weighing scale beam Il), which beam is hung from a fixed frame comprising four posts I I extending upwardly from a base I2 and arranged in pairs, the posts of each pair being joined by cross bars I3 and I4, which bars are in turn joined by a pair of rails I 5 and I8 which extend parallel to and above the scale beam I0. The hoppers are supported at points which are fixed lengthwise of the scale beam, but the proportions of materials delivered should be susceptible to variation to any desired extent, say from a ratio of 1:1 to a ratio of 100:1, the scale beam remaining in balance during any such delivery. To this end, the scale beam pivot point is capable of such adjustment that the distances from said pivot to the hopper support points respectively can be made inversely proportional to any desired delivery ratio. In the illustrative devices for this purpose shown in the drawings, the scale beam I0 is supported from the rails IS-I 6 by means of a carriage identified generally by the numeral Il. Said carriage comprises side plates I8 and I9 joined at their upper ends by a top plate 20 in which there are supported rollers 2I and 22 which ride on the upper surfaces of rails I5-I6. Side plates I8 and I9 extend downwardly adjacent the outer faces of rails I5-I6 and below said rails are joined by a plate 23 which forms a support for a carriage traversing mechanism comprising a screw 24 secured at one end in cross bar I4 and received in a threaded member 25 held in a support 26 secured to the carriage plate 23.

Member 25 is arranged for manual rotation through a suitable crank applied to a stub shaft 21 which is supported in the carriage side plate I9 and has secured thereto a bevel pinion 28 meshing with a bevel pinion 29 secured to a stub shaft 30, which stub shaft also carries a bevel pinion 3| meshing with a bevel pinion 32 associated with member 25.

The scale beam I0 is carried on rollers 33 pivoted in a plate 34 which is joined to the carriage side plates i8 and I 9 through brackets 35 and adjustable connector members 36. The connector members, one of which is placed on each side of the scale beam, are designed to provide iiexing sections 3l which, while of adequate tensile strength, are sufficiently iiexible to provide for the desired tilting movement of the scale beam. In the particular embodiment shown in the drawings, each of the connectors 3E is comprised of a single piece, the end portions of which have a circular cross-section while the midportion .31 is reduced to a blade-like section. Any other desired flexing support may be provided.

It will be understood Vthat the lower plate 34 is traversed with and forms a part of carriage il except that it is tiltable with respect to the upper portion of said carriage by the pivotal movement '1 are secured upstanding posts 3 of the scale beam. To provide for traversing plate 36 in unison with the upper portion of the carriage, a screw 39 secured to an arm il@ depending from the scale beam is received in an interiorly threaded boss di carried in a bracket d2 depending from plate 36. Screw 39 has a bevel gear connection with a stub shaft t3 held in plate 34 and rotated by a flexible shaft connection with the stub shaft 3B, the lower connector of the exible shaft being shown at lle.

To provide for the preliminary balancing of the scale beam, as different initial loads are applied thereto, a variable weight lib carried on a holder @il comprising a flexing section fl'l is hung from a carriage l supported on the scale beam through rollers e9 and traversed by means of a screw E@ received in a threaded member 5i associated with carriage d8 and rotatably mounted in a bracket 5f. secured to the scale beam. lt will be noted that the scale bearn iii is comprised of two similar spaced channels which are secured together by suitable means, such as the arin and the screw supporting bracket 52. Extending between these channels is a guide rnernber 53 the 'length of said scale beam. A fragment oi U thesmaller or alloy hopper, with its support material delivery devices, is shown in Fig. ld adjacent the right end of Fig. l (see also 2), and corresponding parts associated with the larger sponge hopper are shown in Fig. la toward the left in Fig. l. The two hoppers and associated parts being substantially similar, a description of one of them, usually the alloy hopper, will suffice. Like numerals with a prime addition have been used for the sponge hopper devices.

To a hollow flanged boss 563 attached to the scale beam is secured the upper end of a support Vmember 55 which, like the supporting members i, comprises a thin flexing section 56. The lower end of support is secured to a cross-"member such as I-bearn ill. Adjacent the ends of beam 55 which are preferably of tubular construction. For greater rigidity, diagonally disposed brace members, one of which is shown at 5&3, may further join beam 5l and tubular posts 58. Guide links and (il pivoted in coupling `plates E2 and d3 secured adjacent the Vends of Vbeam El substantially prevent transverse and .longitudinal movement of beam l and associated parts. Links d@ and @i are pivotally joined to posts 655 and E5 carried by fixed parts of vthe machine frame or base. The pivotal connections of said links and cli are provided with ball bearings or equivalent anti-friction devices, so vthat they offer a minimum of resistance to the movement of the scale beam.

Branch supports, fragments of which are shown at e9 and le', preferably also tubular, are secured to the tubular posts 53 and E8' at appropriate points in their length, and the upper ends kof members 58', l-i and lil are secured to a hopper Supporting ring l i which may be conveniently made frorn'channel stock. Lateral move- Ament A.of hopper .supporting ring il is prevented by suitable means, such as nexible stranded wires, one ci which is shown yat i2', said wires being joined to A.brackets fit and le' 4secured respectively tothe hopper .ring and to xed parts on the'machine frame.

:Each of .the hopper supporting vrings receives the upper portion of a hopper l5, a convenient means of supporting a hopper i5 and its ring H comprising a bead or ilange 'ld secured to the top of the hopper. Material is delivered from each hopper through a hopper spout or throat 'El to a horizontally disposed tube l which contains a. conveyor screw i9. Each delivery tube l5 extends through a fixed wall ce which may be associated with a melting furnace or feed box therefor. The hoppers, delivery passages and space beyond wall dil form part of a closed controlled atmosphere system. Since each tube le is supported from .its hopper, which in turn is supported from the tilting scale beam, the connection between tube i3 and iixed wall et must be a flexible one. Such a connection inay comprise a bellows all, one end iiange of which is secured to wall Se, while the opposite end flange is secured to tube l. There being adequate clearance within the bellows between tube le and the margins of an aperture 3i in wall Se through which said tube extends.

In the operation of the equipment there is at different tinies substantial variation in the fluid pressure within the closed furnace and the material delivery system, To guard against overinoveinent of bellows di under such varying pressure, suitable support means are provided between the two flanges of the bellows. Such vmeans may comprise .thrust rods 83 having conical .ends which taire into conical depressions in said flanges and flexible wires Sli secured in said ilanges respectively. En view of the rounded or conical ends of the thrust rods t3 which iitin the aforementioned corresponding r cesses, and in. vie-w of the flexible wires k35i which are secured to the flanges of the bellows, preferably in the neighborhood of the rods 33, such flanges are capable of shifting in substantially parallel planes a sulcient amount Vto accommodate the weighing movement of the weighing system. Wide variations in pressure thus will not cause excessive expansion and contraction of the bellows 8! and will permit such movement only within the limits allowed by the aforementioned rods 83 and wires That is, the flanges of the bellows are capable of moving toward one another only to the extent permitted by the rods 817i, and conversely such flanges can move away from one` another only to the extent permitted by the wires 84. Such movement is restricted -to a -very small amount thereby avoiding the exertion of undesired forces upon a hopper, as at l5. It will `be understood that the movement ofthe scale beam and associated parts is only a few thousandths of an inch, thus such connecting parts as links et, @i and l2, bellows 3i, and universal joints Se (to be described), do not citer an appreciable resistance to the desired scale beam movement.

Each of the conveyor screws 'i9 is driven through a universal joint @5 from a stub shaft which carries a worm gear ,Se driven by a vworm pinion 8l carried on la stub shaft Si@ which is connected through universal joint 3S with a drive shaft 89, dri en through a second universal joint i389 from a suitable source of power, such as -a motor 9U and gear box Si (Fig. 3). The presence of the two universal joints 88 and 836i enables the free movement with the scale beam of stub shaft 31e and Vparts driven thereby. @ne of the feed screw drive shafts, preferably the shaft'BB' associated with the Yingredient delivered in .the

greater quantity, may be directly connected to vgear box or variable speed `drive 9i by suitable means, such as belt 92. 'Ille invention contemplates that the second feedscrew drive yshaft 8% be driven at a speed which is varied by the deflection of the scale beam. The system is balanced to provide for delivery of ingredients in certain proportions. Any variation from the desired proportions results in a deviation from Standard of the relative weight of materials remaining in the hoppers and the delivery tubes, and such a variation deilects the scale beam I0. Means are provided whereby the displacement, velocity or acceleration of said beam controls the rate of delivery of one of the ingredients. In the present embodiment of the invention, this is accomplished by varying the rate of rotation of the feed screw 89 in response to the extent of departure of the scale beam from a balanced condition. The element responsive to the departure of the scale beam from balance is a strain gage 95 which is applied to a flexing element 95, one end of which is secured to the scale beam through post 9'! while the opposite end is secured to the fixed rail I6 through bracket 98. One way of causing variations in the current in the strain gage circuit 99 to vary the movement of feed screw drive shaft 89, is to place in the driving train for said member 89, a differential gear device 0|, and to rotate an appropriate element |02 of the differential gearing by means of a servo-motor |93, which is actuated from the current in circuit 99 through appropriate devices, preferably standard commercial instruments. be of conventional design having a normally stationary spider or frame element which when stationary permits rotation of the input and output shafts at a one-to-one ratio. 'I'he spider element, of course, can be rotated and the extent of such rotation is algebraically added or subtracted to the rotation of said output shaft, depending upon the direction of rotation of the spider element. For example, the variations in the current in circuit 99 may be applied to a measuring and self-balancing potentiometer P, and the deflection of the potentiometer transmitted to an electronic bi-directional motor control |03, the output of which is applied to the servo-motor through connecting wires |00. The servo-motor may rotate in either direction, according to the direction of deflection of scale beam I 0, thus either accelerating or retarding the rotation of driven shaft |04 and feed screw drive shaft 39 with respect to their normal rate A of rotation when the servo-motor is stationary.

It will be noted that the motors and parts driven thereby, including the driven ends of shafts 89 and 89', are supported from fixed mounts, while the driven elements of universal joints 88 and 88 are supported indirectly from the scale beam. The shafts 89 and B9' being horizontally disposed and connected through the pairs of universal joints 88-880 and 88'-880, the resistance to deflection of the scale beam by the feed screw drive means is negligible.

What is claimed is:

1. Apparatus for the simultaneous and continuous delivery of materials from at least two separate hoppers in preselected gravimetric ratio comprising in combination: a scale beam having a fulcrum; means for adjusting the position of such fulcrum lengthwise of said scale beam; a pair of hoppers for such materials; means for operatively associating said hoppers with said scale beam on opposite sides of said fulcrum, the moment arms of said hoppers about said fulcrum bearing a ratio to one another in accordance with the adjustment of the position of said fulcrum; power means for effecting positive delivery from The differential device l0 can 9 said hoppers each at a separate basic rate, such rates being at a ratio which is the inverse of the aforementioned ratio of said moment arms, said hoppers being initially charged with such material and said scale beam initially being in a balanced condition; an outfeed rate control means operatively connected to at least one of said positive delivery means for varying the basic delivery rate thereof; and means for governing said delivery rate control means in response to the extent of departure of said scale beam from a balanced position.

2. Apparatus fer the simultaneous and continuous delivery of materials from at least two separate hoppers in preselected gravimetric ratio comprising in combination a scale beam having a fulcrurn: means for adjusting the position of such fulcrum lengthwise of said scale beam; a pair of hoppers; means for operatively associating said hoppers with said scale beam on opposite sides of said fulcrum; means for effecting positive delivery from said hoppers each at a separate basic rate, such rates being at a ratio which is inversely proportional to the ratio of the moment arms of the respective hoppers about said fuicrum, said hoppers being initially charged with such material and said scale beam initially being in a balanced con-dition; balance control means operatively connected to at least one of said positive delivery means; means for varying the basic delivery rate thereof; and means for governing said balance control means in response to the extent of departure of said scale beam from a balanced position.

3. Apparatus for the simultaneous and continuous delivery of materials from at least two separate hoppers in preselected weight ratio comprising: a scale beam having a fulcrum; means for adjusting the position of such fulcrum lengthwise of said scale beam; a pair of hoppers; said hoppers being mounted on said scale beam on opposite sides of said fulcrum, the moment arms of said hoppers about said fulcrum bearing a ratio to one another in accordance with the adjustment of the position of said fulcrum; means having a common power source for effecting positive delivery from said hoppers each at a separate basic rate, such rates being at a ratio which is the inverse of the aforementioned ratio of the moment arms; control means operatively connected to at least one of said positive delivery means for varying the basic delivery rate thereof; and means for governing said control means in response to the extent of departure of said scale beam from a balanced position.

RICHARD E. EVANS. PAUL F. DARBY. THOMAS G. OWEN.

References Cited in the file of this patent UNITED STATES PATENTS 

